three-fold - central processing unit machine have been a never-ending part of the Mac landscape since Apple put a pair of 500MHz G4 chips into a Power Mac back in 2000 . But that landscape shifted Wednesday when Apple introduce a refreshen Power Mac line of credit built around double - core chips .

Apple’sPower Macsnow feature dual - core 2.0GHz and 2.3GHz PowerPC chips from IBM . There ’s also a twofold - core , double - processor 2.5GHz simulation , which Apple is touting as the Power Mac G5 Quad . The machines are powered by threefold - core processors that IBM introduced in July , in brief after Apple announced it would use Intel - built CPUs in its hardware starting in 2006 . And it ’s very potential that some succeeding Intel - based Mac systems will also take advantage of dual - pith technology .

So what ’s the difference between a dual - centre organization and one build around three-fold processors ? And more significant to Mac substance abuser used to get word that two CPUs are better than one , how will dual - inwardness improve the overall execution of their machines ?

One chip , two processing units

First , the setup : rather of having two processors in two separate sockets on a computer ’s motherboard , a dual - kernel scheme has one strong-arm CPU in one single socket — but with two self-governing processing units inside it . This can lay aside distance and money .

A dual - core chip shot can also let the two CPUs parcel memory hoard and bus connections to the system , a cost and design advantage . Otherwise , the arrangement ’s hardware looks middling much the same , whether it ’s a twofold - core or dual - C.P.U. frame-up .

Dual - core may be a new addition to the Mac platform . But on the PC side , Intel and AMD have been supplying microcomputer manufacturer with treble - pith chips in late years . It ’s been a way for chipmakers to render high - performance without high heat .

For that reason , a double - meat crisp makes a slew of gumption for Apple . Today ’s double - processor setups pose several big problems , starting with the fact that the two chips throw off a pot of oestrus , ask immense heat sinks and extra cooling system system . Thus a three-fold - CPU set - up limits Apple ’s plan options , while boost costs .

A threefold - core group chip , on the other hand , potentially frees up Apple to create brawny auto that will be smaller than today ’s Power Mac G5 models , says Roger Kay , president of food market research house Endpoint Technologies Associates . “ Most users would rather have the same power in a smaller organization , ” Kay says . “ Unless you need redundant space for cooling , you could get rid of it . ”

Performance boosts

It will take some time for those size advantages to appear — the Power Macs bring in by Apple Wednesday hold the 20.1 - by-8.1 - by-18.7 - inch dimensions of the previous framework . However , Apple is already taking advantage of the fact that a dual - core chip match two CPUs in the blank space of a exclusive chip ; instead of shrinking the size of it of the box , Apple rather announced the Power Mac G5 Quad , which fills the place that once held two CPUs with two dual - core chips , for a full offourprocessing social unit .

By combining two processor cores on a undivided Si chip , Apple say a dual - nucleus processor can deliver double the computational major power of a single - core CPU . In the case of the Power Mac G5 Quad , applications are able to take reward of four 1 MB L2 cache , four 128 - bit Velocity Engines , and eight double - precision floating - point units , boosting performance over a single - burden , dual - C.P.U. scheme .

Still , today ’s dual - core chips are n’t perfect yet . So chipmakers are working on new generations of eminent - performance , lower - business leader double - core — include Intel , Apple ’s CPU supplier set off next year .

One problem with many of the double - nub chips now available : Intel and AMD poker chip ca n’t run as tight as a undivided core processor ( made using the same manufacturing process and the same aim architecture as the dual - inwardness chip ) , because they ’d lead too hot and require too much power , says Kevin Krewell , editor program - in - chief of the Microprocessor Report . Today ’s dual - cores are n’t running at their top clock stop number potential . So some apps , including many games , still hunt faster on a PC using single pith chip . Mac drug user have to hold off for testing of the new Power Mac G5s to see how IBM ’s dual - core processor get along in this regard — but it ’s interesting to mark that the new duple - core G5 mainframe top out at 2.5 gigacycle per second , compared to 2.7GHz for the previous top - of - the - bank line single - core G5 chip .

With twofold - pith - power PCs , drug user see the most performance profit when using practical program that have been multi - threaded to take vantage of the two cores . That ’s a hopeful development for Mac users since many of their programs have already been rewritten to recognise and take advantage of multiple central processing unit , thanks to the teemingness of treble - processor Power Macs . And those Mac apps will recognise and bug into the benefit of the two CPUs whether you ’re using a double - central processing unit machine — or a dual - core motorcar . Because of OS X ’s symmetric multiprocessing , the operating organisation itself can also direct individual tasks to different cores . This means one process or software can be directed to one core , and a different job to another heart and soul . Other programs that have n’t been multi - threaded will run on a treble - core organisation just as they would a double - processor machine ; they just wo n’t take full - advantage of the benefits .

Many mainstream PC applications have n’t been released in multi - wind translation yet — but the ones that have lean to be in the arenas of creative arts and scientific discipline and engineering science — two markets where the Mac is super popular .

“ laborious - obligation applications , such as those that use TV , will benefit from a dual - core chip because the arrangement can throw more HP at the applications programme or throw one core at the software , and commit the other core to maintain system task , ” says Shane Rau , Program Manager for PC Semiconductors at securities industry research firm IDC .

Looking ahead

It ’s fair to say treble - core be the way of the future tense for the major chipmakers , who are take over the design scheme to keep create meaning carrying into action gains . “ Just increasing clock frequence , which has driven much of the carrying into action increase over the last decennary , has become unattractive due to the extra power necessary , ” Microprocessor Report ’s Krewell says . “ ho-hum clocked dual - core CPU can still extend performance increases with multi - threaded program program . ”

Dual - core group engineering science really start out interesting — and really occupy a big step forward of dual - processor organization — with Intel ’s next - coevals processors , expected in the second one-half of 2006 . They ’re design from the ground up to consume less tycoon and run much cooler . ( These downcast - power dual - core chips are code - key “ Merom ” for notebooks and “ Conroe ” for desktop . ) While the exact timing and details of Apple ’s transition to Intel chips remains under wraps , it ’s safe to don that the changes to the Power Mac system of rules signal a foresightful - term interest in dual - core engineering on the part of Apple .

And that ’s fortunate since Intel intend to make its intersection occupation ( except for Celeron chips , design for the lowest- cost PCs ) completely dual - core by the close of 2006 . AMD will likely follow a similar scheme , Krewell says .